Project Grant NNX07AI57G

THE EARTH MAINTAINS AN INCOMPLETE RECORD OF ITS OWN BOMBARDMENT BUT THE ANCIENT ROCKS OF THE MOON MARS AND THE ASTEROIDS PRESERVE ABUNDANT EVIDENCE OF IMPACT CRATERS AND THEIR PRODUCTS THAT REFLECT HOW THEIR SURFACES HAVE EVOLVED OVER 4.5 BILLION YEARS.IMPACT-MELT ROCKS FROM THESE BODIES PROVIDE THE KEYS TO UNDERSTANDING AND UNRAVELING THE EARLY BOMBARDMENT HISTORY OF THE INNER SOLAR SYSTEM INCLUDING THE TIMING AND NATURE OF THE IMPACTORS. THE WORK IN THIS PROPOSAL WILL INVESTIGATE THE BOMBARDMENT HISTORY OFTHE INNER SOLAR SYSTEM BY CHARACTERIZING THE GEOCHEMISTRY AND GEOCHRONOLOGY OF IMPACT MATERIALS FROM THE EARTH MOON AND ASTEROIDS.WE WILL CONDUCT AGE DATING USING LASER 40AR-39AR METHODS ON SAMPLES FROM THE MOON AND THE UREILITE PARENT BODY USING TECHNIQUES FOR SMALL SAMPLES WE HAVE DEVELOPED SPECIFICALLY FOR THIS WORK. WE WILL COMPLEMENT THIS EFFORT WITH NEW CAPABILITIES TO OBTAIN MINORAND TRACE-ELEMENT CONCENTRATIONS ON THESE SAME MATERIALS BY SECONDARY ION MASS SPECTROMETRY (SIMS) AND INDUCTIVELY COUPLED PLASMAMASS SPECTROMETRY (ICP-MS) TO MEASURE ELEMENT CONCENTRATIONS AS SMALL AS PARTS PER TRILLION AND REDOX STATE USING MOSSBAUER SPECTROSCOPY. TOGETHER THIS POWERFUL ARSENAL OF TECHNIQUES BROUGHT TO BEAR ON A STATISTICALLY SIGNIFICANT NUMBER OF SMALL SAMPLES WILLPROVIDE A FULLER UNDERSTANDING OF THE EARLY BOMBARDMENT ENVIRONMENT (AND HOW FAITHFULLY IT IS PRESERVED IN THE SAMPLE RECORD) ON THE MOON ASTEROIDS AND THE INNER SOLAR SYSTEM.